1. Field of the Invention
The invention generally relates to the technique of carrier aggregation, and more particularly, to wireless apparatuses, wireless systems, and methods for managing the activation and deactivation of multiple component carriers.
2. Description of the Related Art
The Universal Mobile Telecommunications System (UMTS), which evolved from the Global System for Mobile communications (GSM) and belongs to one of the third-generation (3G) mobile communication technologies, utilizes the core network of the GSM system and Wideband Code Division Multiple Access (WCDMA) technology to provide high transceiving rates and optimal service quality. Generally, in a UMTS system, a mobile communication device, or so-called a User Equipment (UE), has to perform a connection establishment procedure to obtain mobile communication services from a service network.
According to release 7 of the 3rd Generation Partnership Project (3GPP) specifications for the UMTS system, the logical channels comprise a Dedicated CHannel (DCH) and a Downlink Shared CHannel (DSCH). A UE may determine from system broadcasts, whether or not a base station supports the DSCH, and may configure the DSCH as the default downlink channel, if the base station supports the DSCH. To further clarify, in a connection establishment procedure as shown in FIG. 1, a UE first transmits a Radio Resource Control (RRC) CONNECTION REQUEST message to a base station in a service network. In response to the RRC CONNECTION REQUEST message being accepted by the service network, the UE receives an RRC CONNECTION SETUP message from the service network. Next, the UE establishes a connection with the base station according to the configurations indicated in the RRC CONNECTION SETUP message. Note that, since the RRC CONNECTION SETUP message is delivered on the DSCH, the UE needs to monitor the DSCH for receiving subsequent response messages after transmitting of the RRC CONNECTION REQUEST message. After the connection is successfully established, the UE further transmits an RRC CONNECTION SETUP COMPLETE message to the service network, to end the connection establishment procedure.
In another situation where network congestion occurs, the UE may receive an RRC CONNECTION REJECT message instead of the RRC CONNECTION SETUP message, as shown in FIG. 2. However, the RRC CONNECTION REJECT message does not indicate which downlink channel (e.g. the DSCH, DCH, or both) the network congestion has occurred on, according to the release 7 of the 3GPP specifications for the UMTS system. As a result, the UE may only continue to retransmit the RRC CONNECTION REQUEST message for a predetermined number of times, until the RRC CONNECTION SETUP message is received or the predetermined number of times is reached.